Pass Labs Int 25 vs Int 60

@bluorion With any Nelson Pass design you should assume it'll get pretty warm.  I think his general rule is to keep it around a level where you can keep your hand on the heat sinks for about 5 seconds before being forced to pull away.  I've had an XA-25 in my room, and it wasn't crazy hot, but I don't think you'd want to stuff it in a cabinet or anything.

Just an update. I have had many amps in for review over the last few months and the INT-25 is still tops in my book for a few reasons. 

I have an INT-250, INT-25, XP-10 and XA 60.8's, a couple of Tube integrated, a Schiit Freya + and Aegir. I have a Yamaha integrated here as well as a Cary 300 SEI. 

Running these into my Heresy IV and LaScala AL5's the INT-25 is amazingly sweet. The INT-250 is neck and neck and provides a bit more bass heft but loses a but of that sweetness than the 25 excels at. The separates of XP-10 and XA60.8 are all about smooth and density. I love those as well but at the end of the day when you favor in cost, heat. and cost to run the INT-25 truly wins if you are running speakers that are not so demanding. 

For the $$ it's tough to beat in the integrated world. I have become a huge fan of Pass Labs and to date have-not heard any other products or brands that I prefer when it comes to amplification. Nelson Pass IS INDEED a genius.

The Heresy IV and LaScala AL5 are easy to drive speakers with a high sensitivity of 99dB and 105dB respectively, and a nominal impedance of 8 ohms. With these speakers it is not a surprise the Pass Labs INT-25 sounded best in comparison to all other higher spec amps which include the INT-60 and 250. Imagine using flea-powered tube amps with the Klipsch horn speakers. With these high sensitivity horns, other high powered amps will have the potential of sounding aggressive.

Move to more conventional harder to drive speakers with 86 to 88dB and lowish impedance of say 4 to 6 ohms perhaps dropping down to 3 ohms minimum, the tables will likely be turned as the INT-25 takes a back seat while the larger amps which include Luxman L-590AXII sounding better with these select speakers. Think Dynaudio, B&W, Marten etc. as these speakers will have the tendency of sounding flat and lifeless if they don’t get enough current and drive from the amp.

By the way Steve, I bought the Luxman L-590AXII after reading your review of the amp on your page. Your high praise on the amp was spot on as the Luxman sounds very good with my Marten Duke 2. I was actually deciding between Pass Labs INT-60 and Luxman L-590AXII and picked the latter as the opportunity came up. The rest was history.

I’m sure the INT-60 or INT-250 will sound equally good if not better but the Luxman has managed to get me off the merry-go-round of upgrades..

I have an INT60 which is just a fantastic integrated. I decided to get it over the INT25  because of the balanced inputs and also preamp Out and power amp Input which the INT 25 doesn’t have. I plan to play with some tube preamps to see if I prefer it. If so, I may go to separates and maybe even monoblock 60.8 amps. The INT 60 was a good launching point and will likely sell for close to what I bought it for. 
Presently I am using my INT 60 with Tannoy Yorkminster’s, Audio Note 3.1 balanced DAC running JPRiver or Tidal Hirez. Also some vinyl..